1. Field of the Invention
This invention is related to copolymers for use in paper coating formulations to improve and optimize paper properties such as sheet gloss, ink gloss and smoothness, to a process for the preparation of the copolymers and to paper coating compositions.
2. Prior Art
Paper coating formulations which comprise latex copolymers are used extensively by the paper industry. Improvements in properties such as sheet gloss, ink gloss and smoothness are continuously sought after through the development of new latexes for inclusion in paper coating formulations.
Coated cellulosic web or paper web is prepared utilizing a pigment, such as clay, and other components which stabilize and disperse the pigment in a water slurry. The slurry is formulated with a binder to produce the coating color, a paper coating composition which is used to coat the web or paper. The components of the coating color contribute to the performance of the process of coating the web, and to the performance of the coated paper. If the paper is a higher quality grade paper, the finished coated web should have a high degree of brightness, smoothness and gloss, as well as a good finish and feel after the web is calendered.
The coating color must have sufficient strength and binding capability to enable printing of the coated paper without "picking", i.e., without the coating separating from either the paper surface or from within the coating.
U.S. Pat. No. 4,440,896, discloses the use of water-soluble polymers of ethylene glycol in binder formulations comprising a latex.
U.S. Pat. No. 4,717,502, discloses the use of polyethylene glycol in aqueous optical brightener compositions.
Japanese Kokai No. 62-169868 discloses the use of acrylate polyethylene glycol polymers in paint formulations.
It would be desirable to have new latexes which provide improved physical characteristics for paper coating formulations and coating colors without the prior art disadvantages associated with admixture of polyethylene glycols therein.